title: Regional differences in veins wall viscosity, compliance, energetics and damping: analysis of the pressure-diameter relationship during cyclical overloads.
abstract: BACKGROUND
  The characterization of the dynamic process of veins walls is essential to understand venous functioning under normal and pathological conditions. However, little work has been done on dynamic venous properties.
  
  
  OBJECTIVE
  To characterize vein compliance (C), viscosity (eta), peak-strain (W St) and dissipated (W(D)) energy, damping (zeta), and their regional differences in order to evaluate their role in venous functioning during volume-pressure overloads.
  
  
  METHODS
  In a mock circulation, pressure (P) and diameter (D) of different veins (anterior cava, jugular and femoral; from 7 sheep), were registered during cyclical volume-pressure pulses. From the P-D relationship, C, W(St) and zeta (at low and high P-D levels), eta and W(D) were calculated.
  
  
  RESULTS
  For each vein there were P-dependent differences in biomechanical, energetics, and damping capability. There were regional-differences in C, eta), W(St) and W(D) (p<0.05), but not in zeta.
  
  
  CONCLUSIONS
  The regional-dependent differences in dynamics and energetics, and regional-similitude in damping could be important to ensure venous functioning during acute overloads. The lower C and higher W(St) and W(D) found in back-limb veins (femoral), commonly submitted to high volume-pressure loads (i.e. during walking), could be considered relevant to ensure adequate venous system functionality and venous wall protection simultaneously.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. yana@fmed.edu.uy
authors.forename: Yanina
authors.initials: Y
authors.lastname: Zócalo
authors.forename: Daniel
authors.initials: D
authors.lastname: Bia
authors.forename: Sebastián
authors.initials: S
authors.lastname: Lluberas
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Armentano
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology*; D003187:Compliance; D005268:Femoral Vein / Q000033:anatomy & histology / Q000502:physiology*; D007601:Jugular Veins / Q000033:anatomy & histology / Q000502:physiology*; D012756:Sheep; D014682:Vena Cava, Inferior / Q000033:anatomy & histology / Q000502:physiology*; D014783:Viscosity